Nanoimprinted superlattice metallic photonic crystal as ultraselective solar absorber
- Johannes Kepler Univ., Linz (Austria)
- Technical Univ., Vienna (Austria)
- Univ. of North Carolina, Chapel Hill, NC (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Here, a two-dimensional superlattice metallic photonic crystal (PhC) and its fabrication by nanoimprint lithography on tantalum substrates are presented. The superior tailoring capacity of the superlattice PhC geometry is used to achieve spectrally selective solar absorption optimized for high-temperature and high-efficiency solar-energy-conversion applications. The scalable fabrication route by nanoimprint lithography allows for a high-throughput and high-resolution replication of this complex pattern over large areas. Despite the high fill factor, the pattern of polygonal cavities is accurately replicated into a resist that hardens under ultraviolet radiation over an area of 10 mm2. In this way, cavities of 905 nm and 340 nm width are achieved with a period of 1 μm. After pattern transfer into tantalum via a deep reactive ion-etching process, the achieved cavities are 2.2 μm deep, separated by 85–95 nm wide ridges with vertical sidewalls. The room-temperature reflectance spectra of the fabricated samples show excellent agreement with simulated results, with a high spectral absorptance approaching blackbody absorption in the range from 300 to 1900 nm and a steep cutoff. The calculated solar absorptivity of this superlattice PhC is 96% and its thermal transfer efficiency is 82.8% at an operating temperature of 1500 K and an irradiance of 1000 kW/m2.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Energy Frontier Research Centers (EFRC) (United States). Solid-State Solar-Thermal Energy Conversion Center (S3TEC)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0001299
- OSTI ID:
- 1459181
- Journal Information:
- Optica, Vol. 2, Issue 8; ISSN 2334-2536
- Publisher:
- Optical Society of AmericaCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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